There has been a significant trend to the use of more perishable, fresh, chilled (and frozen) foods, beverages and temperature sensitive biomedical and pharmaceutical products, compared with the temperature stable, processed or preserved substitute products. At the same time there is an increasing concern by consumers and governments to ensure the quality and safety of these temperature sensitive perishable products, is not jeopardised by hazardous handling prior to consumption. New temperature management tools are useful to minimise these handling hazards in domestic and international trade.
Various types of temperature measurement and recording equipment have been used in the past for this task and record of these are discussed below.
The family of portable reusable data loggers that are placed in perishable product consignments by the shipper to be retrieved and the stored temperature and time data downloaded by either linking to a programmed personal computer, or by removing a printed chart, have been in use by the food and pharmaceutical industries for many years. These robust, portable recorders arc expensive and need to be returned to the shipper on consignment completion. Additionally the data is not accessible until the logger is ultimately read and this maybe after a product recall or hold, should have been triggered. This means that the monitoring devise cannot be as widely used as safe product temperature management directs.
Refrigerated transportation vehicles and shipping containers used for perishable goods transfer have recording chart thermometers for recording the temperature of the interior space. These charts are specific for each vehicle in the cold chain and do not capture the product consignment temperature and time as the product moves between vehicles in the supply chain. It is therefore difficult to marry the charts with specific consignments on other than a post-mortem basis which is not as responsive as industry shippers would like, in terms of being able to anticipate and respond to potential temperature abuse hazards during distribution. As such they do not provide a seamless data stream throughout cold chain distribution
The cumulative time and temperature effect is also indicated by a chemically based product, Monitor Mark™. These time/temperature integrators are monitoring tools that provide a visual, non reversible, indication of time and temperature exposure above a pre-set threshold temperature. This is accompanied by the appearance and migration of a blue colour, left to right through a series of viewing windows on a rectangular flat laminate containing layers of paper film, adhesive and other active chemical components. These strips are typically 96 mm by 20 mm and while relatively inexpensive, only indicate, as distinct from measure, product exhibiting time temperature abuse sensitivity and represent a signal as to when product quality should be checked prior to use.
The temperature, time and location state of air-freight consignments of perishable products are also recorded in a specially designed aluminium ‘Envirotainer’. This is a returnable unit, typically owned by the airline, and is a capital expensive solution to the problem of temperature management for just a part of the cold chain.